Alphatec slides after announcing $300 mln convertible debt deal

** Shares of medical device firm Alphatec Holdings ATEC down 10.4% post-market to $11 on planned capital raise

** Spinal surgery imaging system provider says offering privately $300 mln 5-yr convertible bonds (CBs)

** It plans to use portion of net proceeds to pay for capped calls, to repurchase portion of outstanding 0.75% CBs due 2026, remainder for general purposes

** Carlsbad, California-based firm has ~144.15 mln shares outstanding for ~$1.8 bln market cap, per LSEG data

** ATEC shares on Mon closed down 2.1% at $12.27

** YTD, stock up ~35%

** Avg rating among 12 analysts is "buy" and median PT is $18.92 - LSEG